title: Immediate loading after implant placement following tooth extraction up-regulates cellular activity in the dog mandible.
abstract: OBJECTIVE
  The aim of this study was to investigate cellular activity of the cervical portion of peri-implant tissue due to immediate loading after implant placement following tooth extraction from the dog mandible, in terms of morphological, immunohistochemical and molecular characteristics.
  
  
  METHODS
  A sand-blasted implant was inserted into the root septum bone of each extraction socket and was connected to a superstructure made from resin and then covered with an expanded polytetrafluoroethylene membrane. Implants without the superstructure were used as the non-loading control group. Animals were sacrificed 1-3 weeks later and specimens were observed using light microscopy and mRNA levels were analyzed by real-time polymerase chain reaction.
  
  
  RESULTS
  The new bone formation ratio in the loading group at 3 weeks was significantly higher than in the non-loading group. Alkaline phosphatase (ALP)-positive cells were observed in tissues around the implant surface in both groups at each of the time periods. More osteocalcin (OCN)-positive cells were observed in the non-loading group than in the loading group at 2 weeks. The expression of ALP mRNA in the loading group was significantly up-regulated compared with the non-loading group (P<0.05). The expression of OCN mRNA in the loading group was significantly up-regulated compared with the non-loading group at 2 weeks (P<0.05).
  
  
  CONCLUSIONS
  These results suggest that immediate loading after implant placement following tooth extraction osteogenic affects cellular activity of cervical portion of peri-implant tissue.
authors.affiliation: Department of Clinical Pathophysiology, Tokyo Dental College, Chiba, Japan.
authors.forename: Ryuta
authors.initials: R
authors.lastname: Sato
authors.forename: Kenichi
authors.initials: K
authors.lastname: Matsuzaka
authors.forename: Eitoyo
authors.initials: E
authors.lastname: Kokubu
authors.forename: Takashi
authors.initials: T
authors.lastname: Inoue
mesh_terms: D000469:Alkaline Phosphatase / Q000378:metabolism; D000704:Analysis of Variance; D000818:Animals; D001641:Bicuspid; D003758:Dental Implantation, Endosseous / Q000379:methods*; D019250:Dental Implants, Single-Tooth; D003799:Dental Stress Analysis; D004285:Dogs; D007150:Immunohistochemistry; D008334:Mandible / Q000601:surgery*; D008567:Membranes, Artificial; D015675:Osteocalcin / Q000378:metabolism; D011138:Polytetrafluoroethylene; D012333:RNA, Messenger / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D018709:Statistics, Nonparametric; D013499:Surface Properties; D014081:Tooth Extraction; D020390:Tooth Socket / Q000601:surgery*; D015854:Up-Regulation
chemical_list: D008567:Membranes, Artificial; D012333:RNA, Messenger; D015675:Osteocalcin; D011138:Polytetrafluoroethylene; D000469:Alkaline Phosphatase